I've never looked for a flask, but I'd be interested if anyone knew where to get them. The only thing I can think of is Things Remembered. Probably not the best flasks, but at least meant to be engraved...
As a jewelry store we can get something of a discount on these. I know we had to sign up, and they still aren't cheap. I was looking at pewter steins. Good luck, wish I had a better answer too!
I'm not sure where to get them but I have heard the stainless ones from Walmart were impossible to engrave so make sure you don't get too involved in any stainless one until you know it is engravable.
I have a stainless flask here with three cuts on it. I will cut 440c blade steel, 303 stainless, and other difficult metals. After 3 cuts I gave up on the flask. I think I resharpened something like 20-25 times in those 3 lines.
Rex is right stay way from the stainless ones. Not only is that stainless hard, it vibrates like crazy even when you fill them with sand.
Personally if he insist on flask, I would insist on something soft like either pewter or sterling.
Ray
PS> as a side note. If you decide to go with the stainless flask you may be able to engrave initials on those with a Hermes type machine.... but I give you fair warning you don't want to try and hand engrave them.
Here is a little bit of variety of just flasks. They have pewter which may be a safe bet for the engraving work. I don't know what you call inexpensive, but at $50, these didn't seem to be outrageous.
A call to them may help with a correct material for hand engraving.
I have bought some from here. I have not tried to engrave them but the price is right. They are thin. They use to have 6oz. flasks but I don't see them. I have both. They are stainless.
But at the price you can afford to practice. https://www.outdoorbunker.com/SearchResults.asp?Search=flask&Submit=Search
T
Pewter may cut easy and look nice but don't keep anything in it for very long,it tends to add an unpleasant taste to good whiskey or whatever you put in it. I might suggest stainless but add a silver plaque to engrave on if you can.The flasks that I made are now in the possession of new owners and are very costly,not really practical for this application unless you got a bucket of spare cash!!!!!
I found this one at Academy Sports if I recall. I filled it with water and didn't cut it very deep at all. I found another more recently at the Walmart camping section. Problem is, they are poorly made. You'd need to look through several to get a "good" one.
Thanks everyone. The cheap part isn't me. The groom is purchasing these and paying for an expensive honeymoon. Lolls like I might need to give him an assist.